Pressure activated closure lock

ABSTRACT

A safety lock for a pivoted door (16) closing an opening in a pressure vessel (10) to prevent the door from being opened when pressure in the vessel is above a selected level. A handle (44) is pivotably supported relative to the opening and movable to a locked position in which the door cannot be opened. A pressure lock housing (50) extends from the pressure containment vessel, the housing having a cylindrical opening therein, the axis of which intersects the plane of pivotation of the handle. A piston member (102) is received in the cylindrical opening (98) and has a portion extending externally of the housing. A tubular member (122) carried by the handle is engaged by the piston member when the handle is in the locked position, and pressure within the containment vessel forces the piston member outwardly to thereby prevent the handle from being moved towards the unlocked position. The piston member is automatically retracted when the pressure in the containment vessel is below a safe level.

BRIEF SUMMARY OF THE INVENTION

A safety problem frequently encountered in the gas processing andtransportation industry, particularly in the operation of pipelines, isthat of preventing injury to workmen when a door is opened to a pressureretaining vessel. In many applications it is necessary that ready accessbe provided to the interior of pressure vessels such as for theinsertion or removal of pipeline pigs. For this reason, doors providingsuch ready access must be quickly opened and closed. Otherwise, too muchtime is consumed in removing and reinstalling closures in the pressureretaining vessels. A common means of providing access to the interior ofa vessel, such as a pipeline, is to mount a hinged door abuttable with aflange with a clamping mechanism to securely clamp the periphery of thedoor to the flange. By pivotation of a handle the clamping flange canquickly be removed, after which the door freely swings open. Adifficulty, however, is that if a workman swings the handle to unlatchthe door, and if pressure exists within the pipeline or other vessel towhich the flange is affixed, the door will be blown open, causingserious injury.

In order to attempt to prevent accidents of this type, it has been acustom to install pressure indicating instruments in the vicinity ofaccess doors so workmen can visually determine if pressure exists in thevessel before the locking mechanism holding the closure in place isremoved. A problem with such precaution, however, is that workmenfrequently forget to look at the instrument and assume that there is nopressure within the vessel.

The present invention provides a means of ensuring that a closed doorcovering an opening in a pressure containment vessel cannot beinadvertently opened if pressure exists within the vessel above a safe,preselected level.

The invention is formed as a part of a door which is hinged to apressure vessel such as a flange which provides access to the interiorof the pressure vessel. The flange and the door, when the door is inclosed position, form an abutted peripheral radially extending surfacewhich is held in closed position by semi-circular ring members having aC-shaped cross-sectional configuration. The ring members are pivoted toeach other at one side and are secured by a toggle mechanism at theother side. A handle extends from the toggle mechanism. When the handleis in the closed position the toggle mechanism forces the semi-circularring members together, holding the door in a sealed, locked position.When the handle is swung about its pivotal support it removes force onthe toggle mechanism, allowing the semi-circular ring members to bespread apart, removing the clamping action of the door against theflange and permitting the door to be opened.

A pressure lock housing extends from the pressure containment vessel andhas a cylindrical opening in it. Reciprocally positioned within thecylindrical opening is a piston member. A spring within the pressurelock housing urges the piston member inwardly. When pressure existswithin the interior of the containment vessel, the piston member isforced outwardly against the resiliency of the spring. The handle has atubular locking member which, when the handle is in closed position, isin axial alignment with the piston. When the handle is closed andpressure exists within the containment vessel, the piston member extendsinto the tubular locking member, preventing the handle from being moved.Thus, safety and security of the device is achieved to preventinadvertent injury to a workman attempting to open the door whenpressure exists in the containment vessel.

In a preferred arrangement the pressure lock housing has a secondcylindrical opening communicating with the interior of a containmentvessel in such a manner that the first cylindrical opening extends atright angles to the second cylindrical opening. Positioned within thesecond cylindrical opening is a second piston, a portion of whichextends exteriorly of the housing and has a knob on it. Fluid fills thearea between the second piston and the first-mentioned piston. Pressurewithin the containment vessel first displaces the second piston which inturn causes displacement of the first piston to intercept the handletubular locking member as previously indicated. The knob attached to theexternally extending portion of the second piston provides a visualindication of the existence of pressure within the vessel, augmentingthe locking function of the first piston. In addition, an operatorwishing to test the amount of pressure within the vessel can physicallyinwardly depress the knob, depressing the second piston against pressurewithin the vessel, so that a manual test of the vessel pressure can bemade by the workman to reinforce the workman's awareness of thepossibility of existence of pressure within the containment vessel.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a door closing the end of atubular pressure vessel, such as to provide access to the interior of apipeline or the like.

FIG. 2 is a top plan view of a door closing the end of the tubularpressure vessel of FIG. 1.

FIG. 3 is a cross-sectional view of the locking mechanism as taken alongthe line 3--3 of FIG. 1 and showing the mechanism in the conditionwherein the pressure in the containment vessel is below a preselected,safe level.

FIG. 4 is a cross-sectional view as in FIG. 3 but showing the conditionof the safety lock when the pressure in the vessel is above thepreselected safe level.

FIG. 5 is a cross-sectional view taken along the line 5--5 of FIG. 3showing more details of the pressure actuated closure lock.

DETAILED DESCRIPTION

Referring to the drawings, and first to FIGS. 1 and 2, a closure for apressure containment vessel is shown with an improved pressure activatedlock to prevent the inadvertent opening of the closure when unsafepressure exists within the vessel. As shown in FIG. 2, the pressurevessel is indicated by the numeral 10, and such vessel may be part of apipeline system, a short length of piping communicating with a tank, orany other pressure retaining system as employed in industry. Theillustrated arrangement of FIGS. 1 and 2 is particularly exemplary ofthe type of mechanism employed in the pipeline industry to afford accessto the interior of a pipeline such as for inserting or retrieving apipeline pig. Extending from the vessel 10 are brackets 12 supporting ahinge pin 14. A door 16 closes the open end of the pressure vessel 10,the door being supported by a plate 18 to the hinge pin 14. Thus thedoor 16 can be pivoted to and away from the open end of the vessel aboutthe hinge 14.

As shown in FIG. 3, the vessel 10 terminates with a flange 20 having aperipheral radially extending lip 22. In like manner, the door 16 has aperipheral circumferential radially extending lip 24. The lip portions22 and 24 are of equal diameter. When the door 16 is in closed position,as shown in the drawings, the abutted lip portions 22 and 24 provide aradially external circumferential portion which is engaged bysemi-cylindrical clamp members 26 and 28. As shown in FIG. 3 the clampmembers are C-shaped in cross-sectional configuration so that when inposition around the peripheral aubtment of the door 16 and flange 20,the lip portions 22 and 24 are held in engagement with each other andthe door 16 is securely locked in position. To provide leakproofengagement of the door 16, a circumferential gasket 30 may be employedas shown in FIG. 3.

The semi-cylindrical clamps are hinged together by means of brackets 32and 34 connecting to a hinge bolt 36. The upper end of semi-cylindricalclamp 26 receives a bracket 38 connected to a yoke 40. Another bracket42 extends from the upper end of clamp 28 and is engaged by a toggleaction arrangement controlled by means of a handle 44. When the handle44 is pivoted upwardly about its pivot bolt 46, the toggle arrangementpermits the yoke 40 to be separated from bracket 42 allowing thesemi-circular clamps 26 and 28 to be spread apart, releasing their holdon the door 16, thus permitting the door 16 to be pivoted open. To aidin the pivotal opening and closing of door 16 a grab bar 48 is provided.The specific arrangement of the toggle mechanism including the brackets38 and 42, and yoke member 40 is not a part of this invention as thetoggle mechanism may be constructed in a variety of ways. Sufficient itis to say that the pivotation of handle 44 serves to allow clamps 26 and28 to be loosened from engagement with the door and flange, allowing thedoor to be opened. When the handle 44 is in the closed or downwardposition as shown in FIGS. 1 and 2, the clamps 26 and 28 are locked inposition and the door 16 cannot be removed.

The function of this invention is to prevent handle 44 from being movedfrom the closed position as shown in FIGS. 1 and 2 when a preselectedunsafe level of pressure exists within the pressure containment vessel10. A pressure lock housing is generally indicated by the numeral 50. Asshown in FIGS. 2 and 3, the pressure lock housing is mounted in a shortflange 52 secured in an opening 54 formed in the pressure vessel 10.Extending from the flange 52 is housing 56 having an integral flangeportion 58. By means of bolts 60, the housing 56 is held in position.

An axial opening 66 is formed in the housing 56. The lower portion ofopening 66 adjacent to the lower end of the housing is of enlargedinternal diameter at 68 providing a cylinder which reciprocally receivesa piston 70. Extending coaxially from the piston 70 is piston rod 72.The outer end 74 of the piston extends externally of housing 56. Affixedto the outer end portion 74 of the piston rod is a knob 76 held in placeby means of a set screw 78.

The area of axial opening 66 adjacent the upper end 80 of housing 56 isof reduced internal diameter providing a cylindrical surface 82. Agroove receiving an O-ring 84 is formed in the cylindrical surface 82 toseal against piston rod 72. To further prevent the possibility ofcontamination passing into the interior of the housing opening 66, wiperwashers 86 are employed which engage the portion of the piston rod 72extending externally of the housing 56.

To ensure leakproof engagement of piston 70 with the cylinder wall 68 anO-ring gasket 88 is positioned in a groove formed in the cylinder wall.Thus the area of the internal opening 66 in the housing between O-ringgasket 84 and O-ring gasket 88 is closed and confined. Since piston 70is of larger diameter than the piston rod 72, upward movement of thepiston and piston rod reduces the volume of the area defined by walls 66and 68.

Formed in the housing 56 is a threaded opening 90. Received in opening90 is the external threaded end portion 92 of a tubular element 94. Themember 94 has internal opening 96 therein which reduces to a smallerdiameter opening 98. The difference between the diameters of the openingportion 96 and 98 provides an internal circumferential ledge 100.

Received within the tubular element 94 is a second piston 102 having anintegral enlarged diameter portion 104 at the inner end. Enlargedportion 104 functions as a guide rather than as a piston and has flatson opposite sides so that fluid can flow past the guide into theinterior 96 of the tubular element. The pressure of fluid within opening96 functions on piston rod 102 to urge it outwardly. An O-ring 106contained in a groove in the cylindrical opening 98 forms a seal withthe external surface of the piston rod 102. To prevent the possibilityof contamination of the piston rod moving within the cylinder 98, wiperrings 108 are employed.

A compression spring 110 is received about the second piston 102 andextends between the ledge 100 and the enlarged diameter guide portion104 so that the piston is urged inwardly.

Formed in the wall of the housing 96 are two smaller diameter threadedopenings 112 and 114, each of which receives a zert fitting 116 and 118.The fittings are used to inject fluid into the openings 66 in the bodywhich also fills the larger diameter portion 68 above piston 70 and theinterior of opening 96 in the tubular element 94. By the use of the twofittings, the fluid (preferably such as hydraulic fluid) can be injectedinto fitting 116 until it flows out through fitting 118, therebyensuring that the entire interior is completely filled with fluid. Thefittings 116 and 118 may be of the type such as used for fillinghydraulic brake systems for automobiles wherein the fitting can beloosened to permit the fluid flow therethrough, but when tightenedprohibits fluid flow.

Affixed to handle 44 is a plate 120 extending in the plane of pivotationof the handle. Radially extending from the plate 120 is a tubular member122 of internal diameter sufficiently large to telescopically receivesecond piston 102.

A guide 122 is secured to the semi-circular clamp 28 to ensure that thehandle 44 is maintained in the plane of pivotation about the handle axisformed by bolt 46.

OPERATION

With the door 16 in closed position and with the clamps 26 and 28secured around it and in engagement with the lip portion 22 of flange20, the door is in closed position. To secure the clamps 26 and 28towards each other and securely around the door and flange, the handle44 must be pivoted downwardly to the closed position as shown in FIG. 1.In this position the tubular element 122 is in direct axial alignmentwith second piston 102.

When pressure exists within the interior of the pressure containmentvessel 10, force is applied against piston 70, displacing it upwardly asshown in FIG. 4. This upward displacement also displaces fluid above thepiston in the cylinder 68 and in opening 66, causing the fluiddisplacement to apply increased hydraulic fluid pressure which can onlybe compensated for by increase in volume by the outward extension ofsecond piston 102. This extends the second piston 102 into the tubularfitting 122. In such position handle 44 cannot be moved from its closedposition, thereby preventing the door 16 from being inadvertentlyopened.

The displacement of piston 70 and piston rod 72 by the effect of fluidpressure within the housing outwardly displaces the knob 76 giving avisual indication to the operator that pressure exists within theinterior of the containment vessel 10. The operator may test thestrength of this pressure manually by inwardly depressing the knob 76.In this way if the knob can be relatively easily depressed, the operatorknows that only a low pressure exists; but if the inward manualdepression of knob 76 is difficult, the operator knows significantpressure exists. In any event, the warning is given to the operator thatthe pressure within the vessel 10 must be exhausted before the doorwhich provides access to the vessel can be safely opened.

When the pressure within the vessel 10 is reduced below a safe level,spring 110 urges the second piston 102 in the direction towards firstpiston rod 72, thereby also downwardly deflecting piston 70 andwithdrawing piston rod 102 from within the tubular element 122. Thus thehandle 44 can then be rotated freely to the open position to allow thedoor to be removed.

The invention provides a method of preventing a door closing a pressurecontainment vessel from being inadvertently opened when an unsafe levelof pressure exists within the vessel and at the same time provides amethod of giving a visual indication of the existence of vessel pressureand a method of manually verifying the level of the pressure within thevessel.

The manual verification can, of course, be in conjunction with apressure gauge (not shown) connected to the vessel 10. All of suchdevices help make the operator more cognizant of the potential danger ofattempting to open door 16 if an unsafe pressure level exists within thevessel.

While the invention has been described with a certain degree ofparticularity, it is manifest that many changes may be made in thedetails of construction and the arrangement of components withoutdeparting from the spirit and scope of this disclosure. It is understoodthat the invention is not limited to the exemplified embodiments setforth herein but is to be limited only by the scope of the attachedclaim or claims, including the full range of equivalency to which eachelement thereof is entitled.

What is claimed:
 1. Safety apparatus for use to close an opening in apressure containment vessel comprising:a door sealably engageable withan opening in a pressure containment vessel, the door being pivotallysupported to move to and away from a closed position; a handle pivotallysupported relative to the opening and moveable to and away from a lockedposition in which said door seals the opening; a pressure lock housingaffixed to and extending from the pressure containment vessel, thehousing having a cylindrical opening therein the axis of whichintersects the plane of pivotation of said handle, a fluid communicationchannel connecting the cylindrical opening with the interior of thevessel; a piston member reciprocally received in said cylindricalopening and having a portion extending sealably exteriorly of saidhousing; means of biasing said piston inwardly; and means carried bysaid handle engageable by said piston whereby when the handle is in saidlocked position such means is engaged by said piston member when thepressure within said vessel is above a preselected level and said handlecan be moved from the locked position only when the pressure in thevessel is below the preselected level.
 2. The safety apparatus accordingto claim 1 wherein said means carried by said handle is a tubular memberwhich telescopically receives said piston member when said handle is inthe locked position and the pressure in said vessel is above thepreselected safe opening level.
 3. The safety apparatus according toclaim 1 wherein said pressure lock housing has a second cylindricalopening therein, one end of such second cylindrical openingcommunicating with the interior of said pressure containment vessel, theother end of such second cylindrical opening communicating with saidfirst-mentioned cylindrical opening;a second piston in said secondcylindrical opening, the area within said pressure lock housing betweensaid first and second pistons being filled by a liquid, whereby pressurewithin said containment vessel above a preselected level displaces saidsecond piston which in turn displaces said first piston to cause theportion of said first piston extending externally of said housing toengage said handle means.
 4. The safety apparatus of claim 3 whereinsaid second piston has a portion extending sealably externally of saidpressure lock housing; anda knob affixed to said portion of saidexteriorly extending portion of said second cylinder providing means ofverifying whether or not the internal pressure in said containmentvessel is above the preselected safe opening level.
 5. A closure for theopen end of a tubular pressure vessel comprising:a closure door hingedto the exterior wall of the pressure vessel and pivoted to an openposition in which the vessel open end is exposed and a closed conditioncovering the vessel open end; a pivoted handle moveable to a closedposition when said door is in the closed condition to sealably lock saiddoor to the pressure vessel and moveable to an open position permittingsaid door to be pivoted away from said pressure vessel open end; atubular pressure lock housing extending from the exterior sidewall ofthe pressure vessel adjacent to and spaced from the vessel open end, thelock housing communicating with an opening in the vessel sidewall; atubular cylinder member extending radially from and communicating withsaid pressure lock housing; a piston slideably and sealably received inand extending partially externally of said cylinder member; means onsaid handle engaged by said piston when outwardly extended; and means ofbiasing said piston inwardly whereby when said door is in the closedposition and said handle is in the locked position the handle isprevented from being moved from the locked position as long as pressurewithin said vessel is above the preselected level which overcomes saidbiasing means.
 6. A closure for the open end of a pressure vesselaccording to claim 5 wherein said tubular pressure lock housing providesan internal cylindrical area, and including:a second piston memberreciprocally received in said pressure lock housing cylindrical area, aportion of said second piston extending sealably externally of said lockhousing, the area formed within said pressure lock housing and saidcylinder member between said first-mentioned and said second pistonmember being filled with hydraulic fluid whereby the outwarddisplacement of said second piston by pressure in said vessel outwardlydisplaces said first-mentioned piston by hydraulic action.
 7. The safetyapparatus according to claim 5 wherein said means carried by said handleis a tubular member which telescopically receives said piston memberwhen said handle is in the locked position and the pressure in saidvessel is above the preselected safe opening level.
 8. A closure for theopen end of a pressure vessel according to claim 5 including:a handengageable knob means affixed to said externally extending portion ofsaid second piston.